Velocity governor with anticipatory action



Oct; 10, 1939. c. RI HANNA 2,175,837

VELOCITY EDVERNOR WITH ANTICIPATORY ACTIO Filed Sept. 16, 1937 WITNESSES! INVENTOR 'w- WZM C/l' fan 1? Hanna.

Patented Oct. 10, 1939 vsnocrrr covanivoa'wrm am'norra'rony ACTION Clinton R. Hanna, Pittsburgh, Pa., assignor to Westinghouse Electric 8: Manufacturing Company, East Pittsburgh, Pa., in corporation of Pennsylvania Application September 16, 1937, Serial No. 164,161

7 Claims.

My invention relates to centrifugal speed governors for controlling the speed of regulated devices, such as prime movers.

. Governors of the centrifugal type usually possess hunting characteristics. caused by the necessity of an appreciable departure in the speed of the regulated device from its desired value before a corrective force is developed of suflicient intensity to produce the necessary corrective action, and the inability of this corrective force, once it is established, to discontinue its influence prior to a completion of the correction. Thus, the inertia of the corrective force causes overcorrection or hunting.

II In such regulators the accuracy of regulation may be greatly improved if the speed controlled mechanism is responsive not only to variations in speed from the desired value, but also to the acceleration that anticipates such speed changes,

a and which occurs as the speed of the regulated member starts away from its desired value. The force of acceleration may become effective before any substantial change in the speed of the regulated device has occurred, and may, there- 35 fore, be employed to introduce a corrective influence into the regulator system earlier than would be the case if the regulator responded to speed variations alone.

Such speed governors are also frequently subject to errors occasioned by the effect of gravity on the inertia elements.

It is an object of my invention to provide a centrifugal speed governor that is responsive both to the regulated quantity, and to the rate of change of that quantity from its desired value.

Another object of my invention is to provide a centrifugal speed governor of the indicated character that is balanced as to gravity vibrations.

My invention will be better understood by reference to the accompanying drawing, in which:

Figure 1 is a diagrammatic view of one embodiment of the invention, certain parts thereof being shown in section and certain parts in elevation;

Fig. 2 is an end view of the regulator illustrated in Fig. 1; and

Fig. 3 is a perspective view of the abutments supporting the inertia members.

Referring to Fig: l, a motor I is illustrated having an armature winding 2 and a' field winding 3 that are supplied with energy from a source represented by the conductors 4 and 5, a regulating resistor 6 being provided in series circuit relation with the field winding 3. The motor I may be provided with a shaft 1 to which the regulating structure is attached by means of a sleeve ii carrying a disc member 9 that is driven in accordance with the speed of' the motor. The regulating structure controls a circuit which extends from the lower end of the resistor 6 C through conductor ll, brush l2, collector ring 13, conductor 14, contact members l5 and I6, conductor l1, collector ring it, brush is and conductor 2| to a movable contact member 22 to control the lower portion of the resistor 6 be- I tween the movablecontact member 22 and conductor 5. r

The contact members l5 and 16 are carried by inertia members 23 and 24, respectively, that are mounted upon abutments and 26, which I. extend outwardly from the surface of the disc 9. The inertia members are illustrated as carried by flat springs 21 and 28, the planes of which intersect along a line 29 forming, in effect, a pivot about which the masses 23 and 24 may 80 move. The springs 21 and 28 are fastened to the inertia members by screws 3| and 32 and to the supporting abutment by screws 33 and 34.

It will be noted thatthe abutments 25 and 26 are cut away, leaving a surface 35 on the corner 88 thereof adjacent the line of intersection of the flat springs 28 forming the pivot, thus giving greater freedom of motion to the springs. The crossed fiat springs 21 and 28, in addition to providing a pivotal support for the inertia masses 23 and 24, also provide the biasing force resisting the centrifugal force of the masses and hold them in the position illustrated when at rest.

As the motor is started, centrifugal forces acting on the masses 23 and 24 pull them outwardly from the center of revolution of the disc, each inertia mass being moved in a counter-clockwise direction about its pivot line 29, urging the contact member 15 downwardly and the contact member l5 upwardly, as viewed in the drawing. 40 When the centrifugal forces acting on the masses 23 and 24 become sufficient to bias the fiat springs 21 and 28 supporting them the amount necessary to bring the contact members l5 and I6 into engagement, the portion of the resistor 6 between the movable contact member 22 and the conductor 5 is short-circuited to increase the excitation of the field winding 3 and correspondingly decrease the speed of the motor I. This reduction in speed reduces the centrifugal force sufficiently that the bias of the springs 21 and 28 will overcome this force and cause a separation of the contact members Hand 16.

With the inertia masses 23 and 24 positioned as illustrated in Fig. 2, on opposite sides of their 55 t'll supporting abutments 25 and 226 with respect to gravity, and with the contact members to and it arranged to engage substantially on the ads of rotation of the disc the efiect of gravity on the twomasses will be such as to move the contact members to and iii in the same direction, so that the contact pressure does not change due to the force of gravity. The regulator is, therefore, gravity-balanced, increasing its accuracy of regulation. ihis increase in the accuracy of regulation eliminates the tendency of vibratory engagement and separation of the contact members iii and iii.

It will be noted that the inertia masses 23 and are so positioned that their movements of inertia about the axis of rotation causes an inertia torque to be developed upon a change in angular velocity which biases the inertia masses the one or the other direction about the pivot lines 2Q. Upon an acceleration in the speed of the disc 9, if the disc is rotating in a clockwise direction, as viewed in Fig. 2, this inertia torque moves the masses in a counterclockwise direction about their pivots thus anticipating the increase in speed that will result therefrom and causing an earlier engagement of the contact members l5 and it than would otherwise occur. Since the force due to angular acceleration aids the centrifugal force in bringing the contact members into engagement, the amount of departure in speed from the desired value necessary to initiate a corrective action is reduced. Conversely, upon a decrease in the speed of the disc 9 the inertia torque of deceleration will cause the inertia masses and E i to move in a clockwise direction about their pivot lines to decrease the pressure between the contact members it and it, or cause their separation earlier in the regulating cycle than would be the case if these contact members were responsive to changes in centrifugal force alone.

- The particular speed at which the contact members it and it engage, which corresponds to the speed desired to be maintained on the regulated device, is dependent upon the spring deflection necessary to control the contact members and is determined by the spacing of the contact members to and lb. The further these members are spaced apart when the disc is at rest, the greater is the speed required to produce the necessary centrifugal forces on the members 23 and 24 to flex the springs the amount necessary to bring the contact members into engagement. If it is desired to construct a regulator in which-the contact members l5 and I5 will be in engagement at low speeds and will separate when the desired speed is reached, it is necessary only to position the abutments 25 and 26 on the opposite sides of the inertia masses 23 and 24, respectively, so that the centrifugal force will move the inertia masses in a clockwise direction instead of a counter-clockwise direction about their supporting pivot lines represented by the line 'of intersection of the flat springs 28 and 29.

Many changes in the details of construction illustrated and described will be apparent to those skilled in the art within the spirit of my invention, and I do not wish to be limited otherwise than by the scope of the appended claims.

I claim as my invention;

1. In a speed governor for controlling the speed of a rotating member, two inertia masses mounted to revolve about a common axis in accordance with the speed of the rotating member, biasing means for urging said inertia masses to predetermined positions relative to the axis, said masses being so pivoted with respect to the axis oi rotation as to be urged by centrifugal force against the force said biasing means, said inertia masses having relatively large moments oi inertia about their axis of rotation for efiecting relative movements thereoi about their pivot points in response to angular acceleration, the effect of centrifugal force and the force of angular acceleration on said inertia masses being cumulative during an increase in the speed 0; the rotating member, and means actuated by said inertia masses cooperative for governing the speed of said rotating member.

2. a speed governor for controllin the speed or": a rotating member, an element mounted to revolve in accordance with the speed oi be con-- trolled member, two inertia masses pivotally mounted thereon on opposite sides oi the axis 5 of rotation thereof and having their centers of gravity correspondingly displaced from the radiuspassing through their supporting pivots, biasing means for urging said inertia masses to predetermined positions relative to the axis of rotation, said inertia, masses having relatively large moments inertia about their axis of rotation for effecting relative movements there-- of about their pivot points in response to angular acceleration to effect a bias on the inertia masses about their pivot points that is cumu lative with the centrifugal force during an increase in the s eed or the rotating member, and means actuated by said inertia masses cooperative for governing the speed of said rotating member,

3. in a speed governor for controlling the speed of a rotating member, two inertia masses mov-- ably mounted to revolve about a common in accordance with the speed of rotation of the controlled member, cooperating contact members carried by said inertia masses and positioned to engage substantially at the axis of rotation, biasing means for urging said inertia masses to predetermined relative positions, said inertia masses being so positioned as to be actuated by the cumulative effect of an inertia couple due to centrifugal force and an inertia couple due to the inertia of angular acceleration acting jointly against the force of said biasing means upon changes in speed to control the engagement and separation of said contact members, and means controlled by said contact members for governing the speed of said rotating member.

4. In a speed governor for controlling the speed of a, rotating member, two inertia masses movably mounted on to revolve about a, common axis in accordance with the speed of rotation of the controlled member, cooperating contcct members carried by said inertia, masses and p0 sltloned to engage substantially at the axis of rotation, biasing means for urging said inertia masses to 'a predetermined relative position, said inertia masses being so positioned astomove by centrifugal force against the force of saidblasing means upon changes in speed to control the engagement and separation of said contact members, said inertia masses having relatively large moments of inertia about their axis of rotation for efiectlng relative movements thereof about their pivot points in response to an acceleration that acts cumulatively with centrifugal force against said biasing means, and

Gill

I tating disc, means for driving the disc at a speed oorresponding to 'the speed of a member to be regulated, a pair of inertia masses mounted on tially at the axis of rotation of said-disc, said masses being so positioned with respect to their supporting pivots that the centrifugal force acting thereon upon rotation of the disc, and the torque of angular acceleration thereof each create a force causing an increase in contact pressure'in opposition to the biasing force of said flat springs, and meanscontrolled by said contact members for governing the speed of said member to be regulated.

6. In a regulator, in combination, a member to be regulated, a member rotatively driven at a speed that varies in accordance with the speed of the member to be regulated, inertia means carried by-and pivotally mounted on said last named member and so positioned with respect to the mounting pivot as to form an inertia couple due to the angular torque of acceleration and to form an inertia couple due to centrifugal force that act cumulatively and to be unresponsive to gravity vibration, and means actuated by said inertia means for controlling the member to be regulated.

'7. In a speed regulator, in combination, a member to be regulated, a member rotatively driven at a speed that varies in accordance with the speed of the member to be regulated, inertia means carried by and plvotally mounted on said last named member and arranged to be responsive to the angular torque of acceleration and to centrifugal force, said inertfa means com,- prlsing two elements so positioned that the gravity eiIecton one is compensated by the gravity effect on the other, said two inertia elements being so positioned with respect to their supporting pivots that the inertia couple caused by centrifugal force and the inertia couple caused by the torque of angular acceleration are cumulative on the inertia elements during an increase in speed of the member to be regulated and means actuated by said inertia means for controlling the member to be regulated.

CLINTON R. HANNA. 

